The study is being conducted to evaluate whether African potato, an herbal medicine, can be used together with anti-HIV medicines without affecting the amounts of the anti-HIV medicines in the blood. African potato is an African herbal medicine widely used in Africa, particularly sub-Saharan Africa. Although it has not been proven, it is believed to help boost the immune system. Similar studies have been done on herbal medicines especially those that are used in developing countries. In some cases, the herbal treatments can affect the blood levels of other medicines when the medicines are used together. This study will measure the effect of African potato on lopinavir/ritonavir (Kaletra®), a common anti-HIV medicine. Lopinavir/ritonavir is approved by the United States Food and Drug Administration (FDA). The information obtained from this study will tell us if African potato and anti-HIV treatments can be used together to treat HIV infected patients in Africa and other resource poor regions.